Length Control System and Method

ABSTRACT

A retractable leash device (e.g., for pets, children, or the like) having a length control system for limiting the extendable length of a main line is provided. The device includes a cover plate mounted on a wind-up spool and having at least one ridged channel that interacts with a length control switch during line extension to control the extendable length of the main line while simultaneously maintaining the retractability of the main line.

FIELD OF TECHNOLOGY

The present technology relates to length control systems, and moreparticularly, to retractable leash devices (e.g., for pets, children, orthe like) in which the extendable length of a line therein is shortenedwithout affecting its retractability.

BACKGROUND

The retractable nature of conventional leashes benefits the user byeliminating the excess line that can accumulate when the distancebetween the user and the leashed being (e.g., pet) varies. These devicesfeature a housing with a handle portion that encloses a wind-up spoolbiased to retract an attached fixed length of line. The wind-up spoolextends out line when pulled and retracts the line when tension islessened. The maximum travel of the line in current devices can belimited by the user in two ways: (1) by fully extending the line on thewind-up spool, thus reaching the maximum length of the leash; and (2) byemploying a manually actuated brake mechanism, which locks and fixes thewind-up spool to a set length the user desires. A locking mechanism onthe brake allows the user to lock in place the wind-up spool without theuser having to apply constant pressure to the brake mechanism.

Improvements to retractable leashes are desirable, one benefit of thepresent technology is to provide a new and improved retractable leash.Conventionally, if a user desires to shorten the length of theretractable leash, the user typically employs a manually actuated brakethat can be either locked or held in place manually by applying constantpressure. Shortening the length of the leash is beneficial in situationswhere the user desires the pet or other animal or object connected tothe leash to remain closer so that the user has more control. Shorteningthe leash can be beneficial when the user is in an area with potentialhazards, such as vehicle or bicycle traffic, steep drop-offs or cliffs,other animals or people nearby, and other potential dangers. Shorteningthe leash by means of the brake mechanism, however, freezes the wind-upspool and eliminates the retractable nature of the device, which canresult in the accumulation of excess line in the leash when the distancebetween the user and the pet is lessened, thereby negating the benefitof the device itself. The accumulated excess line caused by thissituation can be dangerous, potentially presenting a tripping hazard tothe user, the pet, or nearby pedestrians. The accumulated line can alsobecome tangled in the pet's feet, forcing the user to halt his or heractivity to untangle the line. Thus, a need exists for a leash in whicha user can have more control over its length, for ease of use.

SUMMARY OF THE TECHNOLOGY

The claimed technologies are (1) a length control system, (2) aretractable leash device in which the length control system is enclosedin a housing, (3) and a method for restricting the movement of a humanor animal using the length control system. The length control system iscomprised of a spool with two opposing parallel surfaces, a centerportion joining the two surfaces; an extendable and retractable mainline coiled around the center portion of the spool; a channel defined onone of the two spool surfaces or on a cover plate affixed to one of thetwo spool surfaces; and a switch configured to interact with the channelto restrict the extension but not the retraction of the main line. Insome embodiments this length control system can be enclosed in a housingto form a retractable leash device. This retractable leash device can beused in the claimed method to restrict the distance that a leashed beingcan travel from the leash holder without restricting the retractabilityof the leash's main line.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technology is discussed in greater detail below withreference to exemplary embodiments illustrated in the accompanyingdrawings, in which:

FIG. 1 is a perspective view of a retractable leash device having a mainline, in accordance with various embodiments of the present technology;

FIGS. 2a and 2b are plan views of a retractable leash device in apartially disassembled state, illustrating a switch in differentpositions of a channel of the device, in accordance with variousembodiments of the present technology;

FIG. 3a is a side view of a retractable leash device, in accordance withvarious embodiments of the present technology;

FIG. 3b is a top view of a switch of a retractable leash device, inaccordance with various embodiments of the present technology;

FIGS. 3c and 3d are side views of a switch, in accordance with variousembodiments of the present technology;

FIG. 3e is a bottom view of a switch, in accordance with variousembodiments of the present technology;

FIG. 3f is a plan view of a side surface of a wind-up spool of aretractable leash device, in accordance with various embodiments of thepresent technology;

FIGS. 4a-8b illustrate the progressing interaction between a switch anda channel during extension and retraction of a main line, in accordancewith various embodiments of the present technology;

FIG. 9a is a side view of a retractable leash device, in accordance withvarious embodiments of the present technology;

FIG. 9b is a top view of a switch of a retractable leash device, inaccordance with various embodiments of the present technology;

FIGS. 9c and 9d are side views of a switch, in accordance with variousembodiments of the present technology;

FIG. 9e is a bottom view of a switch, in accordance with variousembodiments of the present technology;

FIG. 9f is a plan view of a side surface of a wind-up spool of theretractable leash device, in accordance with various embodiments of thepresent technology;

FIGS. 10a-12b illustrate a switch in various positions with respect tovarious channels of a retractable leash device, in accordance withvarious embodiments of the present technology;

FIG. 13a is a side view of a retractable leash device, in accordancewith various embodiments of the present technology;

FIG. 13b is a top view of a switch of a retractable leash device, inaccordance with various embodiments of the present technology;

FIGS. 13c and 13d are side views of a switch, in accordance with variousembodiments of the present technology;

FIG. 13e is a bottom view of a switch, in accordance with variousembodiments of the present technology;

FIG. 13f is a plan view of a side surface of a wind-up spool of theretractable leash device, in accordance with various embodiments of thepresent technology; and

FIGS. 14a-16b illustrate a switch in various positions with respect tovarious channels of a retractable leash device, in accordance withvarious embodiments of the present technology.

DETAILED DESCRIPTION

As used herein, the term “leash” refers to any device having a length,such as a strap or cord, that can be used to restrain a human or animal,including but not limited to a pet or a child. As used herein, the term“retractable” means having a length that can be moved away from, ortowards, a stationary point in a manner that adjusts the distancebetween the stationary point and a point along the length. FIG. 1 is aperspective view of a retractable leash device 100 in accordance withvarious embodiments of the present technology. FIGS. 2a and 2b are viewsof retractable leash device 100 in a partially disassembled state,illustrating a switch 154 in different positions of a channel 152 of thedevice, in accordance with various embodiments of the presenttechnology. Retractable leash 100 can include a housing 101 composed ofopposite housing sides that, when coupled to one another, form a wind-upspool enclosure portion 101 a and a handle portion 101 b. The housingsides can be secured to one another by conventional means, e.g., via oneor more screws or snaps. The second housing side can include one or moreholes on an inner face thereof that align with one or more correspondingholes on an inner face of the first housing side for attachment byscrews. One or more of the holes of the second housing side can includethreads for coupling to corresponding threads of screws, or vice versa.

Referring to FIGS. 1, 2 a, and 2 b, a wind-up spool 140 can be mounted,via a center hole 142, to a column 105 protruding from the inner face ofthe second housing side. A main line 160 can have an end 160 e, and canbe coiled about wind-up spool 140. End 160 e can be coupled to aconnector 165, which can, in turn, be coupled to an extension line 166(e.g., for connecting to a collar, harness, or other restraining systemfor a subject, e.g, an animal, such as a pet or the like) via a link167. Connector 165 can serve as a stopper that prevents end 160 e ofmain line 160 from retracting into housing 101. Retractable leash 100can also include a spring or spring-like mechanism (not visible in thedrawing figures) that provides a constant recoil force for retractingmain line 160 whenever it is extended from wind-up spool 140.

Retractable leash 100 can also include an optional brake mechanism 170having a manually actuated brake switch 172 and brake leg 174. Whenactuated, brake leg 174 can provide frictional forces upon contactthereof with portions of wind-up spool 140 (e.g., with side surfaces ofwind-up spool 140, such as side surface 144), which can preventretraction and extension of main line 160.

To maintain the retractability of main line 160, while simultaneouslylimiting the extendable length thereof, retractable leash device 100 canadvantageously include a length control system. In various embodiments,the length control system can include a channel 152 and a switch 154that interacts with channel 152. As used herein, “interacts with” meansthat a portion or all of the switch contacts a portion of the channel ina manner that is secure but also can slide freely along the length ofthe channel upon application of mechanical force. Channel 152 can bedefined in a cover plate 150 that is mounted to side plate 144 ofwind-up spool 140. Channel 152 (which can be, e.g., a ridged channel)can be defined as a spiral-like curve that extends concentricallyoutward from an inner channel end 152 a (disposed in a region adjacentthe center hole) to an outer channel end 152 b (disposed in a regionproximate the periphery of cover plate 150). In various embodiments,portions of the curve can be equidistant from one another (e.g., by adistance R), or of varying distances from each other, as it spirals fromend to end. Cover plate 150 can be made of any suitable material (e.g.,metal, plastic, or the like), and can be mounted in any suitable manner(e.g., via an adhesive, with one or more clips crews or snaps, or thelike). Cover plate 150 can conform to the circular shape of side plate144, and can include a center hole 151 that aligns with center hole 142of wind-up spool 140 for mounting to column 105. However, cover plate150 can alternatively not include a center hole. For example, in someembodiments, the depth of wind-up spool 140 can span the entirety of (oreven exceed) the height of column 105, in which case, there is no needfor cover plate 150 to have a center hole.

Switch 154 (which can, e.g., be a pin, a nail, or the like) can includea head and a post. The post can be constructed to pass through a lengthcontrol slot 103 on the first housing side, which can be positioned toexternally expose portions of channel 152. When the post is insertedthrough slot 103 and into channel 152, any extension or retraction ofmain line 160 can cause wind-up spool 140 and cover plate 150 to rotate,and thus channel 152 to also rotate with respect to the post. In thecase of main line extension, channel 152 can traverse the post fromchannel end 152 b to channel end 152 a. Put another way, the post cantraverse channel 152 from channel end 152 b to channel end 152 a.Conversely, in the case of main line retraction, the post can, forexample, traverse channel 152 from channel end 152 a to channel end 152b. As illustrated FIGS. 1, 2 a, and 2 b, switch 154 can assume differentpositions in channel 152 (and can move in a generally downward directionin length control slot 103), when main line 160 is extended from housing101. When switch 154 reaches channel end 152 a, movement of wind-upspool 140 may be halted, effectively limiting the maximum extendablelength of main line 160. Having cover plate 150 disposed over side plate144 of wind-up spool 140 can advantageously restrict switch 154 tointeract only with channel 152. Side plate 144 can thus serve as abarrier between the switch's post and main line 160, effectivelypreventing switch 154 from contacting and/or interfering with extensionand retraction of main line 160 during use of retractable leash device100.

The width of channel 152 can be defined such that it is large enough toreceive and guide the post of switch 154. Additionally, the width ofchannel 152 can be uniform throughout its entire length. However, thewidth may vary, and may assume different shapes. In various embodiments,channel 152 can also be smooth, such that the switch's post travelstherein in unimpeded or with minimal frictional forces against the sidesof the channel.

While switch 154 can limit the amount of main line 160 that can beextended from wind-up spool 140, it does not restrict or interfere withthe retractability of main line 160 when it is released from an extendedstate. This is because, as the switch's post traverses in a directionfrom outer channel end 152 b to inner channel end 152 a during main lineextension (that is, as wind-up spool 140 rotates from a position inwhich the post contacts outer channel end 152 b to a position in whichthe post contacts inner channel end 152 a), the post is free toconversely traverse in a direction from inner channel end 152 a to outerchannel 152 b when main line 160 is subsequently released.

The amount of length of main line 160 that is permitted to extend fromhousing 101 can be at least partially controlled by the rotationalposition of cover plate 150 with respect to wind-up spool 140. Forexample, cover plate 150 can be rotationally positioned with respect towind-up spool 140 such that, when main line 160 is fully retracted andconnector 165 abuts (or is disposed proximate to) the slot through whichmain line 160 extends, the post of switch 154 abuts (or is disposedproximate to) channel end 152 b. In this configuration, main line 160can be allowed to extend by a length approximately equal to the lengthof ridged channel 152 from channel end 152 b to channel end 152 a.

Alternatively, cover plate 150 can instead be rotationally positionedwith respect to wind-up spool 140 such that, when main line 160 is fullyretracted, the post of switch 154 is disposed at a distance from channelend 152 b. Here, main line 160 can be allowed to extend by a lengthshorter than the length of channel 152 (from channel end 152 b to thechannel end 152 a), since the length of channel 152 that switch 154 cantraverse during extension of main line 160 is shorter. In this way,depending on how wind-up spool 140 or cover plate 150 is oriented duringmanufacture, the preset extendable length of main line 160 provided bychannel 152 can be different from the length of channel 152 itself.

In some embodiments, rather than being defined on cover plate 150,channel 152 can be defined directly onto side plate 144 of spool 140,rendering a cover plate, such as cover plate 150, unnecessary. In theseembodiments, wind-up spool 140 and cover plate 150 can, in effect,comprise a single component. In these embodiments side plate 144 may bethicker, and its channel may not be defined through the entire thicknessof the side plate, which can avoid the post of switch 154 contactingwith main line 160, disposed on the opposite side of the side plate.

FIG. 3a is a side view of an alternate retractable leash device 200, inaccordance with various embodiments of the present technology. FIG. 3bis a top view of a switch 254 of exemplary leash device 200. FIGS. 3cand 3d are side views of switch 254. FIG. 3e is a bottom view of switch254. FIG. 3f is a plan view of a side surface 250 of a wind-up spool 240of exemplary leash device 200.

Exemplary leash device 200 can include a housing 201 having oppositehousing sides, a wind-up spool 240, a main line 260, and a connector265. In various embodiments, the length control system can include achannel 252 and a switch 254. Switch 254 can be, for example, a manualswitch mechanism that a user can displace by moving or flipping incertain directions.

Referring to FIG. 3f , in certain embodiments, channel 252 can bedefined in a side surface 250 of wind-up spool 240. However, in certainembodiments, channel 252 can alternatively be defined in a cover platemountable or mounted to a side surface 250 of spool 240. Channel 252 caninclude a channel end 252 a and a channel end 252 b having an entry area252 c.

Referring to FIGS. 3b-3e , in certain embodiments, switch 254 caninclude a manual mechanism 254 m, a bottom frame 254 f having a guidepath 254 g, a spring 254 s disposed in guide path 254 g, and a pin 254 phaving a head 254 h disposed in guide path 254 g. As shown in FIG. 3e ,spring 254 s, in its natural state, can apply a force to head 254 h ofpin 254 p and can retain pin 254 p on one side of guide path 254 g.Referring to FIG. 3c , switch 254 can be disposed at a slot 203 suchthat movement of manual mechanism 254 m, disposed on an external side ofhousing 201, can cause pin 254 p, disposed on an internal side ofhousing 201, to traverse guide path 254 g.

The following description of how exemplary leash device 200 can beoperated to limit the extendable length of main line 260, withoutaffecting retractability of the line, is made with reference to FIGS.4a-8b . FIGS. 4a-8b illustrate an exemplary progressing interactionbetween switch 254 and channel 252 during extension and retraction ofmain line 260 from housing 201. In particular, FIGS. 4a and 4b are viewsof exemplary leash device 200, illustrating the interaction betweenswitch 254 and channel 252, when switch 254 is in an unactuated stateand main line 260 has not yet extended from housing 201. FIGS. 5a and 5bare views of leash device 200, illustrating the interaction betweenswitch 254 and channel 252, when switch 254 is in an actuated state andmain line 260 has not yet extended from housing 201. FIGS. 6a and 6b areviews of leash device 200, illustrating the interaction between switch254 and channel 252, when switch 254 is in the actuated state and acertain amount of main line 260 has extended from housing 201. FIGS. 7aand 7b are views of leash device 200, illustrating the interactionbetween switch 254 and channel 252, when switch 254 is in the actuatedstate and main line 260 has extended from housing 201 to a preset lengthdefined by the length of channel 252 between channel ends 252 a and 252b.

Referring to FIGS. 4a and 4b , switch 254 is shown in its unactuatedstate and main line 260 is fully coiled about spool 240. In thisembodiment, spring 254 s is in a relaxed state and applies force to pin254 p, retaining pin 254 p at an upper portion of switch 254. In thisposition, no portion of pin 254 p is in contact with channel 252. Next,when switch 254 is actuated (e.g., via user operation of manualmechanism, 254 m), pin 254 p can compresses spring 254 s and entersentry area 252 c at channel end 254 b of channel 252 (FIGS. 5a and 5b ).After pin 254 p enters channel 252, any extension of main line 260 fromhousing 201 can cause the pin to traverse the channel. As a result, pin254 p can also compress spring 254 s during the traversal. FIGS. 6a and6b depict pin 254 p having traversed to a position in channel 252between channel ends 252 b and 252 a, after main line 260 has extendedfrom housing 201 by a certain amount. As main line 260 continues toextend, pin 254 p can continue to traverse channel 252 until it reacheschannel end 252 a. At this point (FIGS. 7a and 7b ), pin 254 p can fullycompress spring 254 s, traversal of pin 254 p is halted, and furtherextension of main line 260 is restricted. In this way, the lengthcontrol system of leash device 200 can restrict extendibility of mainline 260 to a preset amount that is less than the full length of mainline 260 (see FIG. 7b , where an amount of main line 160 remains coiledabout spool 240). However, the system does not prohibit retractabilityof main line 260 from the state shown in FIGS. 7a and 7b , since releaseof main line 260 can allow a spring mechanism coupled to spool 240 toreturn to its relaxed state, and thus draw the main line back intohousing 201 and around the spool. As main line 260 is retracted, spool240, and thus channel 252, continues to rotate, allowing pin 254 p toreverse its travel path from inner channel end 252 a to outer channelend 252 b. As pin 254 p reverses its travel in channel 252, spring 254 scan continually be decompressed. FIGS. 8a and 8b depict pin 254 p havingreversed its traversal of channel 252 to a position between channel end252 a and 252 b.

FIG. 9a is a side view of an alternate exemplary retractable leashdevice 300, in accordance with various embodiments of the presenttechnology. FIG. 9b is a top view of a switch 354 of leash device 300.FIGS. 9c and 9d are side views of switch 354. FIG. 9e is a bottom viewof switch 354. FIG. 9f is a plan view of a side surface 350 of a wind-upspool 340 of leash device 300.

Exemplary leash device 300 can include a housing 301 having oppositehousing sides, a wind-up spool 340, a main line 360, and a connector365. In various embodiments, the length control system can includemultiple channels 352 a, 352 b, and 352 c, and a switch 354.

Referring to FIG. 9f , in certain embodiments, channels 352 a-c can bedefined in a side surface 350 of wind-up spool 340. However, in certainembodiments, channels 352 a-c can alternatively be defined in a coverplate mountable or mounted to a side surface 350 of spool 340. Channels352 a-c can be connected to one another via a bridge 399. In certainembodiments, channel 352 a can be circular, and channels 352 b and 352 ccan be spiral-like. Given channel 352 a's circular shape, it is merely acontinuous circular path. Channel 352 b can have a channel end b1 and achannel end b2, and channel 352 c can have a channel end c and a channelend c2.

Referring to FIGS. 9b-9e , in certain embodiments, switch 354 caninclude a manual mechanism 354 m, a bottom frame 354 f having a guidepath 354 g, a spring 354 s disposed in guide path 354 g, and a pin 354 phaving a head 354 h disposed in guide path 354 g. As shown in FIG. 9e ,spring 354 s, in its natural state, can apply a force to head 354 h ofpin 354 p and can retain pin 354 p on one side of guide path 354 g.Referring to FIG. 9c , in certain embodiments switch 354 is disposed ata slot 303 such that movement of manual mechanism 354 m, disposed on anexternal side of housing 301, can cause pin 354 p, disposed on aninternal side of housing 301, to traverse guide path 354 g.

The following description of how exemplary leash 300 can be operated tolimit the extendable length of main line 360, without affectingretractability of the line, is made with reference to FIGS. 10a-12b .FIGS. 10a-12b illustrate the interaction between switch 354 and channels352 a-c during extension and retraction of main line 360 from housing301. In particular, FIGS. 10a and 10b are views of leash device 300,illustrating the position of switch 354 with respect to bridge 399 andchannel 352 a, when switch 354 is in an unactuated state and main line360 has not yet been extended from housing 301. In this position and inits unactuated state, any extension of main line 360 will merely causepin 354 p to traverse channel 352 a in circles-channel 352 a does notrestrict the extension of the main line.

FIGS. 11a and 11b are views of leash device 300, illustrating theinteraction between switch 354, bridge 399, and channel 352 b, whenswitch 354 is in an actuated state in a direction −X, and main line 360has not yet been extended from housing 301. When switch 354 is actuatedin the −X direction and main line 360 is being extended, pin 354 papplies a force to spring 354 s in the +X direction and traverseschannel 352 b, beginning at end b1, until the pin reaches end b2. Atthis point, further extension of main line 360 is prevented. In thisway, the length control system of leash device 300 can restrictextensibility of main line 360 to a preset amount that is less than thefull length of main line 360. However, the system does not prohibitretractability of main line 360 when pin 354 p is disposed at end b2,since release of main line 360 would allow a spring mechanism coupled tospool 340 to return to its relaxed state, and thus draw the main lineback into housing 301 and around the spool. As main line 360 isretracted, spool 340, and thus channel 352 b, continues to rotate,allowing pin 354 p to reverse its travel path from end b2 to end b1. Aspin 354 p reverses its travel in channel 352 b, spring 354 s iscontinually relaxed.

FIGS. 12a and 12b are views of leash device 300, illustrating theinteraction between switch 354, bridge 399, and channel 352 c, whenswitch 354 is in an actuated state in a direction +X, and main line 360has not yet been extended from housing 301. When switch 354 is actuatedin the +X direction and main line 360 is being extended, pin 354 papplies a force to spring 354 s in the +X direction and traverseschannel 352 c, beginning at end c1, until the pin reaches end c2. At endc2, further extension of main line 360 is prevented. However, becausechannel 352 c is longer than 352 b, the length control system of leashdevice 300 can restrict extendibility of main line 360 to a preset“intermediate” amount that is less than the full length of main line360, but more than the preset length set by channel 352 b. Additionally,the system does not prohibit retractability of main line 360 when pin354 p is disposed at end c2, since release of main line 360 would allowa spring mechanism coupled to spool 340 to return to its relaxed state,and thus draw the main line back into housing 301 and around the spool.As main line 360 is retracted, spool 340, and thus channel 352 c,continues to rotate, allowing pin 354 p to reverse its travel path fromend c2 to end c1. As pin 354 p reverses its travel in channel 352 c,spring 354 s is continually relaxed.

FIG. 13a is a side view of an alternate exemplary retractable leashdevice 400, in accordance with various embodiments of the presenttechnology. FIG. 13b is a top view of a switch 454 of leash device 400.FIGS. 13c and 13d are side views of switch 454. FIG. 13 e is a bottomview of switch 454. FIG. 13f is a plan view of a side surface 450 of awind-up spool 440 of leash device 400.

Exemplary leash device 400 can include a housing 401 having oppositehousing sides, a wind-up spool 440, a main line 460, and a connector465. In various embodiments, the length control system can includemultiple channels 452 a, 452 b, and 452 c, and a switch 454. Asillustrated in FIG. 13f , channel 452 a is wider than the otherchannels. In certain embodiments, however, all the channels can havevalues within about 5% of each other.

Referring to FIG. 13f , channels 452 a-c can be defined in a sidesurface 450 of wind-up spool 440. However, in certain embodiments,channels 452 a-c can alternatively be defined in a cover plate mountableto a side surface 450 of spool 440. Channels 452 a-c can be connected toone another via a bridge 499. Channel 452 a can be circular, andchannels 452 b and 452 c can be spiral-like. Given channel 452 a'scircular shape, it is merely a continuous circular path. Channel 452 bcan have a channel end d1 and a channel end d2, and channel 452 c canhave a channel end e1 and a channel end e2.

Referring to FIGS. 13b-13e , in certain embodiments, switch 454 caninclude a manual mechanism 454 m, a bottom frame 454 f having a guidepath 454 g, a spring 454 s disposed in guide path 454 g, and a pin 454 phaving a head 454 h disposed in guide path 454 g. As shown in FIG. 13e ,spring 454 s, in its natural state, can apply a force to the head of pin454 p and can retain pin 454 p on one side of guide path 454 g.Referring to FIG. 13c , in certain embodiments switch 454 is disposed ata slot 403 such that movement of manual mechanism 454 m, disposed on anexternal side of housing 401, can cause pin 454 p, disposed on aninternal side of housing 401, to traverse guide path 454 g.

In addition to pin 454 p, switch 454 can include an second pin 554.Second pin 554 can, for example, have a head and a post. In certainembodiments, second pin 554 can be fixed in place relative to frame 454f. When manual mechanism 454 m is moved, second pin 554 can, along withpin 454 p, move in a corresponding manner or can move independently ofeach other.

The following description of how exemplary leash 400 can be operated tolimit the extendable length of main line 460, without affectingretractability of the line, is made with reference to FIGS. 14a-16b .FIGS. 14a-16b illustrate the progressing interaction between switch 454and channels 452 a-c during extension and retraction of main line 460from housing 401. In particular, FIGS. 14a and 14b are views of leashdevice 400, illustrating the position of switch 454 with respect tobridge 499 and channel 452 a, when switch 454 is in an unactuated stateand main line 460 has not yet been extended from housing 401. In thisposition and in its unactuated state, any extension of main line 460will merely cause pin 454 p and second pin 554 to traverse channel 452 ain circles—channel 452 a does not restrict the extension of the mainline.

FIGS. 15a and 15b are views of leash device 400, illustrating theinteraction between switch 454, bridge 499, and channel 452 c, whenswitch 454 is in a first actuated state in a direction +X, and main line460 has not yet been extended from housing 401. When switch is actuatedin the +X direction and main line 460 is being extended, pin 454 papplies a force to spring 454 s in the +X direction and traverseschannel 452 c, beginning at end e1, until the pin reaches end e2. Atthis point, further extension of main line 460 is prevented. During thistime, second pin 554 remains in channel 452 a and traverses the channelin circles. In this way, the length control system of leash device 400can restrict extensibility of main line 460 to a preset amount that isless than the full length of main line 460. However, the system does notprohibit retractability of main line 460 when pin 454 p is disposed atend e2, since release of main line 460 would allow a spring mechanismcoupled to spool 440 to return to its relaxed state, and thus draw themain line back into housing 401 and around the spool. As main line 460is retracted, spool 440, and thus channel 452 c, continues to rotate,allowing pin 454 p to reverse its travel path from end e2 to end e1. Aspin 454 p reverses its travel in channel 452 b, spring 454 s iscontinually relaxed.

FIGS. 16a and 16b are views of leash device 400, illustrating theinteraction between switch 454, bridge 499, and channel 452 c, whenswitch 454 is in a second actuated state in a direction −X, and mainline 460 has not yet been extended from housing 401. When switch 454 isactuated in the −X direction, second pin 554 enters channel 452 b andpin 454 p remains in channel 452 a. When main line 460 is beingextended, second pin 554 traverses channel 452 b, beginning at end d1,until the pin reaches end d2. At this point, further extension of mainline 460 is prevented. Because channel 452 b is shorter than 452 c, thelength control system of leash device 400 can restrict extendibility ofmain line 460 to an amount less than full length of main line 460 andless than the preset length set by channel 452 c. Additionally, thesystem does not prohibit retractability of main line 460 when second pin554 is disposed at end d2, since release of main line 460 would allow aspring mechanism coupled to spool 440 to return to its relaxed state,and thus draw the main line back into housing 401 and around the spool.As main line 460 is retracted, spool 440, and thus channel 452 b,continues to rotate, allowing second pin 554 to reverse its travel pathfrom end d2 to end d1. In certain embodiments, second pin 554 can remainin channel 452 b until manual mechanism 454 m is displaced in the +Xdirection.

In certain embodiments, channels 454 a and 454 b can be separate fromchannel 454 c, with no portion bridging channel 454 c to the other thechannels. In these embodiments, second pin 554 can be a separatecomponent from switch 454, and can be insertable into and retrievablefrom channel 452 b through slot 403 as desired by a user.

Accordingly, embodiments of the retractable leash device advantageouslylimits the extendable length of the main line, without affecting itsretractability.

It will thus be seen that the aspects, features and advantages madeapparent from the foregoing are efficiently attained and, since certainchanges may be made without departing from the spirit and scope of thetechnology, it is intended that all matter contained herein shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A length control system comprising: a spoolcomprising a) two opposing surfaces, substantially parallel to eachother and rotatable around an axis, and b) a center portion joining thetwo surfaces; a main line coiled around the center portion of the spooland extendable and retractable; two concentric channels defined on oneof the two surfaces, and a switch comprising a pin movable toselectively engage each channel, wherein the switch is configured tointeract with either channel when engaged by the user during extensionor retraction of the main line from the spool, thereby restrictingextension of the main line to a predetermined length chosen by the userwithout restricting the retractability of the main line.
 2. The systemof claim 1, wherein the spool comprises three concentric channelsdefined on one of the two surfaces.
 3. The system of claim 1, whereinthe two channels are connected by a bridge.
 4. A length control systemcomprising: a spool comprising a) two opposing surfaces, substantiallyparallel to each other and rotatable around an axis, and b) a centerportion joining the two surfaces; a cover plate mounted to one of thetwo surfaces of the spool; a main line coiled around the center portionof the spool and extendable and retractable; two concentric channelsdefined on one of the two surfaces, and a switch comprising a pinmovable to selectively engage each channel; a switch comprising a pinmovable to selectively engage each channel, wherein the switch isconfigured to interact with either channel when engaged by the userduring extension or retraction of the main line from the spool, therebyrestricting extension of the main line to a predetermined length chosenby the user without restricting the retractability of the main line 5.The system of claim 4, wherein the spool comprises three concentricchannels defined on one of the two surfaces.
 6. The system of claim 4,wherein the two channels are connected by a bridge.
 7. A retractableleash device, comprising a length control system of claim
 1. 8. Aretractable leash device, comprising a length control system of claim 4.9. A method of restricting the movement of a human or animal comprisingthe steps of: attaching a leash device containing the leash controlsystem of claim 1 to the human or animal; and engaging the switch in thechannel to select a predetermined maximum length of the main line.
 10. Amethod of restricting the movement of a human or animal comprising thesteps of: attaching a leash device containing the leash control systemof claim 4 to the human or animal; and engaging the switch in thechannel to select a predetermined maximum length of the main line.